c# - 使用CsvHelper可以将空格转换为可为空的值吗？

我需要解析一些非常la脚的Csv文件。我正在使用CsvHelper，它的功能很棒。除了我的行中有空格，通常我有一个 double 行。

文件:



如果我尝试将其映射到

public class Test
{
  [CsvField(Name = "Text")]
  public string Text { get; set; }

  [CsvField(Name = "SomeDouble")]
  public double? SomeDouble{ get; set; }

  [CsvField(Name = "MoreText")]
  public string MoreText{ get; set; }
}

然后我得到这样的错误:



如我所见，我的选择是创建一个自定义解析器，或将我的值映射到字符串属性中并在那里进行解析。

还有其他选择吗？

如果可以配置将空白视为null，那就太好了。

根据要求，这里是重现该问题的代码示例

 static class Program
    {
        public class Test
        {
            [CsvField(Name = "Text")]
            public string Text { get; set; }

            [CsvField(Name = "SomeDouble")]
            public double? SomeDouble { get; set; }

            [CsvField(Name = "MoreText")]
            public string MoreText { get; set; }
        }

        static void Main(string[] args)
        {
            // create fake in memory file
            var memoryStream = new MemoryStream();
            var streamWriter = new StreamWriter(memoryStream);
            streamWriter.WriteLine("Text,SomeDouble,MoreText");
            streamWriter.WriteLine("Good, 1.23, Good");
            streamWriter.WriteLine("Bad, ,Bad");

            streamWriter.Flush();

            //reset the file to the begining
            memoryStream.Position = 0;

            using (
                var csv =
                    new CsvReader(
                        new StreamReader(memoryStream)))
            {
                // this call will blow up with the exception.
                var records = csv.GetRecords<Test>().ToList();

                //carry on and do stuff with 'records'...
            }
    }

谢谢。

最佳答案

最后，我创建了自己的类型转换器，它将空白与null相同。

public class WhiteSpaceToNullableTypeConverter<T> : TypeConverter where T : struct
{
    public override bool CanConvertFrom(ITypeDescriptorContext context, Type sourceType)
    {
        return sourceType == typeof (string);
    }

    public override bool CanConvertTo(ITypeDescriptorContext context, Type destinationType)
    {
        return destinationType == typeof (T?);
    }

    public override object ConvertFrom(ITypeDescriptorContext context, System.Globalization.CultureInfo culture,
                                       object value)
    {
        T? result = null;

        var stringValue = (string) value;
        if (!string.IsNullOrWhiteSpace(stringValue))
        {
            var converter = TypeDescriptor.GetConverter(typeof(T));
            result = (T)converter.ConvertFrom(stringValue.Trim());
        }

        return result;
    }

    public override object ConvertTo(ITypeDescriptorContext context, System.Globalization.CultureInfo culture,
                                     object value, Type destinationType)
    {
        var result = (T?) value;
        return result.ToString();
    }
}

像这样将其应用于您的模型

public class Test
{
    [CsvField(Name = "Text")]
    public string Text { get; set; }

    [CsvField(Name = "SomeDouble")]
    [TypeConverter( typeof( WhiteSpaceToNullableTypeConverter<Double> ) )]
    public double? SomeDouble{ get; set; }

    [CsvField(Name = "MoreText")]
    public string MoreText{ get; set; }
}

关于c# - 使用CsvHelper可以将空格转换为可为空的值吗？，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/13058269/